1. Field of the Invention
This invention pertains in general to advertising on the Internet and in particular to selecting an advertising message for display in response to a given search query.
2. Background Art
Many web sites provide search engines which accept a keyword-based query from a user and produce a list of matching categories or documents to the user in return. For example, the ALTAVISTA web site contains a search engine that enables a user to execute a query on multiple keywords and receive matching information, such as references to web pages, in response.
Such web sites typically generate revenue by displaying advertising messages, such as banner ads, to the user along with the returned search results. However, users often ignore the ads and may even find the ads irritating. Therefore, web sites strive to display ads related to the search query on the assumption that a user is more likely to show interest in such ads. For example, if the user searches for the phrase xe2x80x9cTahoe ski areas,xe2x80x9d then the user may tend to respond to ads for products such as skis, hotels near Lake Tahoe, etc. because the user is presumably interested in skiing.
To provide this functionality, web sites typically sell keywords to advertisers. An advertiser""s ad is displayed when the user searches on a keyword owned by that advertiser. Since multiple advertisers may desire the same keyword, the web sites often auction desirable keywords to the highest bidders. For example, a web site might auction generic keywords such as xe2x80x9ccarxe2x80x9d and xe2x80x9cautomobile.xe2x80x9d
Still, web sites often display ads that are inappropriate in view of the query received from the user. Sometimes, a particular ad is generally appropriate for many queries and the advertiser therefore buys a large number of keywords for the ad. As a result, other advertisers are blocked from using the keywords for their own, possibly more relevant, ads. In a competitive advertising scenario, for example, a dealer of a first make of automobile might buy the keywords corresponding to other makes, thereby intending to entice buyers away from competing makes. As a result, a user may be annoyed to see ads for the first make of automobile when the user is seeking information about another make.
Moreover, advertisers often have little guidance when selecting keywords and seldom know the characteristics of real-world user queries. As a result, advertisers frequently buy overly general keywords like xe2x80x9ccars,xe2x80x9d on which users seldom query. Consequently, often no advertisers have purchased the exact keywords utilized by the users. Therefore, the web site displays general rotation ads instead of targeted ads.
Therefore, there is a need in the art for a way to increase the relevancy of the selected ads to the query terms received from users. Preferably, a solution to this need will overcome the deficiencies of selecting ads via keywords.
The above need is met by a search engine that probabilistically maps a user query into a category, and then uses the category to select a targeted message. The search engine receives the query terms from the user""s client computer via the Internet. In response, the search engine executes a search on a web directory to locate zero or more documents that match the query terms. The search engine may also search other directories in order to identify web pages or other documents that match the query terms.
If the search engine has located one or more documents matching the query terms, the search engine determines the categories corresponding to the retrieved documents. In a preferred embodiment of the present invention, each document in the web directory is assigned to a category in a hierarchical directory. In one embodiment, the hierarchical directory is derived from information available through the Open Directory Project (ODP). In general, the ODP is a hierarchical directory of web pages assembled by human operators who review the web pages and assign the pages to certain categories.
In an alternative embodiment of the present invention, the hierarchy in the web directory is completely or substantially flat. A flatter hierarchy simplifies the process of selecting a message because a document belongs to only one or a few categories, instead of belonging to a long chain of ancestor categories.
The search engine preferably next selects one of the categories corresponding to the retrieved documents. In one embodiment of the present invention, the search engine selects the category of one of the returned documents at random. Since categories having more documents matching the query terms are more likely to be selected, the random selection probabilistically selects the category best matching the query terms. In alternative embodiments, the search engine uses one or more other heuristics to bias the category selection.
Once the search engine selects a category, it preferably accesses a message database and selects a message associated with the selected category. The message database preferably holds multiple messages, with each message belonging to one or more of the categories enumerated in the web directory. In a preferred embodiment, the messages are banner ads provided by advertisers. Preferably, the advertisers purchase xe2x80x9csharesxe2x80x9d in one or more of the categories for each banner ad. When the search engine selects the category in which a given ad has shares, the search engine selects that ad a number of times proportional to the shares of that category owned by the ad.
The search engine preferably returns a web page containing the document references retrieved from the web directory and the one or more messages selected from the message database to the client. Typically, the web page includes a subset of the document references (e.g., the 10 best matches) and at least one banner ad (i.e., the message). Obviously, the web page can include other message types in addition to or instead of the banner ad and/or a different number of references or messages.